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Fabrication of NASA's pupil mask begins with the preparation of a silicon wafer, which serves as the foundation for the black silicon structure. The wafer undergoes ion beam figuring (IBF), a non-contact technique that precisely removes surface irregularities at the nanometer scale. This process ensures that the silicon surface is diffraction-limited, eliminating errors that could degrade optical performance. Once the wafer is polished to the required precision, it is then processed lithographically to define the mask pattern, creating reflective and absorptive regions essential for controlling light propagation. To achieve the desired high absorption characteristics, the lithographically patterned wafer undergoes cryogenic etching, a sophisticated process that transforms the silicon surface into a highly textured, black silicon structure. This method utilizes a controlled plasma environment with sulfur hexafluoride (SF6) and oxygen to etch the surface at cryogenic temperatures. The process is carefully optimized by adjusting parameters such as gas flow rates, chamber pressure, ion density, and etch duration, leading to the formation of high-aspect-ratio nanostructures on the silicon substrate. These structures, resembling a dense “forest” of silicon nanospikes, trap and diffuse incoming light, drastically reducing specular reflection. The resulting surface exhibits an ultra-low reflectivity that is orders of magnitude lower than conventional polished silicon. By leveraging NASA’s cutting-edge fabrication technique, the newly developed black silicon pupil mask offers a powerful solution for high-contrast astronomical imaging. Its ability to minimize scattered light and enhance optical contrast makes it an ideal component for space telescopes tasked with directly imaging exoplanets as well as other applications requiring ultra low reflectivity systems.